Drug interactions
Levothyroxine + Lycopus
Severity: Moderate
Levothyroxine and Lycopus: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Lycopus (gypsywort) extracts have antithyrotropic activity and may reduce thyroid hormone activity, which could blunt the effect of levothyroxine replacement. Clinical data are limited, so the size of the effect is uncertain.
What this interaction means in plain words
Levothyroxine and Lycopus can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Why it happens
Lycopus constituents may inhibit TSH binding and peripheral T4 to T3 conversion, opposing thyroid hormone action (pharmacodynamic antagonism).
What to do
Avoid combining lycopus with levothyroxine where possible. If used, monitor TSH and free T4 and adjust the levothyroxine dose to the results.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Levothyroxine
Frequently asked questions
Can I take Levothyroxine with Lycopus?
MediHelp rates the interaction as moderate. Levothyroxine and Lycopus can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Lycopus (gypsywort) extracts have antithyrotropic activity and may reduce thyroid hormone activity, which could blunt the effect of levothyroxine replacement. Clinical data are limited, so the size of the effect is uncertain.
How serious is the interaction between Levothyroxine and Lycopus?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid combining lycopus with levothyroxine where possible. If used, monitor TSH and free T4 and adjust the levothyroxine dose to the results.
What other medicines interact with Levothyroxine?
MediHelp also lists interactions of Levothyroxine with, for example, Cholestyramine, Sodium iodide i-131, Tiratricol. The full list is on the Levothyroxine page.
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